Effect of mechanical activation on the structure of pulverized coal and iron ore powder

Abstract

Morphologies and structures of pulverized coal and iron ore powder after mechanical activation were studied by SEM, XRD, FTIR and laser particle sizer. The microcrystalline structure of coal was found to be destroyed by mechanical activation via reducing the pile height and number of layers, and the organic structure of coal was altered through the destruction of the ether bond. Mechanical activation led to distortions and dislocations of the crystal lattice of iron ore, decreasing crystallite size, increasing the grain boundary area, and producing an amorphous phase. These increased the Gibbs free energies of dislocations and grain boundaries as well as the surface Gibbs free energy and the amorphization Gibbs free energy, which would eventually increase the energy stored in iron ore called mechanical storage energy. The longer the mechanical activation process, the higher mechanical storage energy for the iron ore will be saved. The amorphization Gibbs free energy is the biggest among the four kinds of Gibbs free energy, accounting for 94.8% ∼ 87.1% of the total storage energy in the mechanical activated iron ore.

Mechanism on Activation of Coal Gangue Admixture

“…Only few studies have shown that coal gangue can improve its activity through mechanical activation, chemical activation, thermal activation, and microwave activation [7]. e effect of mechanical force in grinding would change the crystal structure and physical properties of minerals in coal gangue; the structures of the Al-O, Al-O-Si, and Si-O bonds on the particle surface are broken, and the surface hydroxyl is eliminated; this situation results in many chemical active points on the particle surface, increasing the surface activity and free energy of live materials [19][20][21].…”